CN103311908B - Single end current is utilized to realize transmission line single-phase high-impedance relay protecting method - Google Patents

Abstract

The invention discloses one utilizes single end current to realize transmission line single-phase high-impedance relay protecting method.First the inventive method measures the faulted phase current instantaneous value of each sampling instant of transmission line current transformer installation place; choose two adjacent cycle faulted phase current sampled values and form Protection criteria; to faulted phase current waveform degree of asymmetry with whether there is discontiguous area and detect; if Protection criteria is set up; then judge transmission line generation single-phase high-impedance; send action trip signal, the circuit breaker at tripping transmission line two ends.The inventive method utilizes single end current to achieve the relaying protection of transmission line single-phase high-impedance, and performance is not subject to the impact of transition resistance and load current, can correct action message during transmission line single-phase high-impedance.The inventive method only need utilize single end current, and without the need to using voltage data, performance is not by the impact of Secondary Circuit of Potential Transformer broken string.<!--1-->

Description

Single end current is utilized to realize transmission line single-phase high-impedance relay protecting method

Technical field

The present invention relates to Relay Protection Technology in Power System field, specifically relate to one and utilize single end current to realize transmission line single-phase high-impedance relay protecting method.

Background technology

The additional impedance that transition resistance produces can have a strong impact on the performance of impedance distance protection.If impedance distance protection tripping when easily causing line protection troubles inside the sample space that the additional impedance that transition resistance produces is resistance sense; If the additional impedance that transition resistance produces be capacitance-resistance when easily causing line protection external area error, impedance distance protection action generation surmounts.

High/super/extreme pressure transmission line of alternation current is also often heavy load transmission line, heavy load electric current can make impedance distance protection malfunction or tripping, and the impact of heavy load electric current on impedance distance protection performance can not be ignored.Overload transmission of electricity situation line fault-free; the measurement impedance of traditional distance protection is owing to affecting meeting substantial deviation actual measurement impedance by overload electric current; easily cause traditional distance protection misoperation; cause grid power blackout expanded range; even cause load to shift in a large number thus threaten circuit normally to run, causing huge potential safety hazard to power grid security.

Summary of the invention

The object of the invention is to the deficiency overcoming prior art existence, provide one to utilize single end current to realize transmission line single-phase high-impedance relay protecting method.First the inventive method measures the faulted phase current instantaneous value of each sampling instant of transmission line current transformer installation place; choose two adjacent cycle faulted phase current sampled values and form Protection criteria; to faulted phase current waveform degree of asymmetry with whether there is discontiguous area and detect; if Protection criteria is set up; then judge transmission line generation single-phase high-impedance; send action trip signal, the circuit breaker at tripping transmission line two ends.The inventive method utilizes single end current to achieve the relaying protection of transmission line single-phase high-impedance, and performance is not subject to the impact of transition resistance and load current, can correct action message during transmission line single-phase high-impedance.The inventive method only need utilize single end current, and without the need to using voltage data, performance is not by the impact of Secondary Circuit of Potential Transformer broken string.

For achieving the above object, the inventive method adopts following technical scheme:

Utilize single end current to realize transmission line single-phase high-impedance relay protecting method, it is characterized in that, comprise following sequential steps:

The faulted phase current instantaneous value of each sampling instant of protector measuring transmission line current transformer installation place, the faulted phase current instantaneous value of each sampling instant utilizing it to measure calculates $\underset{x=0}{\overset{N-1}{\mathrm{\&Sigma;}}}i(t+\mathrm{x\&Delta;t})>k\underset{x=0}{\overset{N-1}{\mathrm{\&Sigma;}}}[i(t+\mathrm{x\&Delta;t})+i(t+\mathrm{x\&Delta;t}-\frac{N}{2}\mathrm{\&Delta;t})]$ With $\underset{x=0}{\overset{N-1}{\mathrm{\&Sigma;}}}i(t+\mathrm{x\&Delta;t})>\mathrm{\&beta;}{I}_e+\mathrm{\&alpha;}\underset{x=0}{\overset{N-1}{\mathrm{\&Sigma;}}}[i(t+\mathrm{x\&Delta;t})+i(t+\mathrm{x\&Delta;t}-N\mathrm{\&Delta;t})]$ Whether set up, if set up simultaneously, then judge transmission line generation single-phase high-impedance, protective device sends action trip signal, the circuit breaker at tripping transmission line two ends simultaneously; Wherein, t is sampling instant; Δ t is sampling interval duration; X is positive integer counter; The faulted phase current sampled value that i (t+x Δ t) is t+x Δ t sampling instant; for the faulted phase current sampled value of sampling instant; The faulted phase current sampled value that i (t+x Δ t-N Δ t) is t+x Δ t-N Δ t sampling instant; N is a cycle sampling number, ; T is the cycle time of fundametal compoment; I _efor transmission line rated current; K is tuning coefficient; α is tuning coefficient; β is tuning coefficient.

Feature of the present invention and technological achievement:

First the inventive method measures the faulted phase current instantaneous value of each sampling instant of transmission line current transformer installation place; choose two adjacent cycle faulted phase current sampled values and form Protection criteria; to faulted phase current waveform degree of asymmetry with whether there is discontiguous area and detect; if Protection criteria is set up; then judge transmission line generation single-phase high-impedance; send action trip signal, the circuit breaker at tripping transmission line two ends.The inventive method utilizes single end current to achieve the relaying protection of transmission line single-phase high-impedance, and performance is not subject to the impact of transition resistance and load current, can correct action message during transmission line single-phase high-impedance.The inventive method only need utilize single end current, and without the need to using voltage data, performance is not by the impact of Secondary Circuit of Potential Transformer broken string.

Accompanying drawing explanation

Fig. 1 is application multi-line power transmission system schematic of the present invention.

Embodiment

According to Figure of description, technical scheme of the present invention is expressed in further detail below.

Fig. 1 is application multi-line power transmission system schematic of the present invention.In Fig. 1, CT is current transformer.The current instantaneous value of each sampling instant of protector measuring transmission line current transformer installation place, the faulted phase current instantaneous value of each sampling instant utilizing it to measure calculates $\underset{x=0}{\overset{N-1}{\mathrm{\&Sigma;}}}i(t+\mathrm{x\&Delta;t})>k\underset{x=0}{\overset{N-1}{\mathrm{\&Sigma;}}}[i(t+\mathrm{x\&Delta;t})+i(t+\mathrm{x\&Delta;t}-\frac{N}{2}\mathrm{\&Delta;t})]$ With $\underset{x=0}{\overset{N-1}{\mathrm{\&Sigma;}}}i(t+\mathrm{x\&Delta;t})>\mathrm{\&beta;}{I}_e+\mathrm{\&alpha;}\underset{x=0}{\overset{N-1}{\mathrm{\&Sigma;}}}[i(t+\mathrm{x\&Delta;t})+i(t+\mathrm{x\&Delta;t}-N\mathrm{\&Delta;t})]$ Whether set up, if set up simultaneously, then judge transmission line generation single-phase high-impedance, protective device sends action trip signal, the circuit breaker at tripping transmission line two ends simultaneously.

Wherein, t is sampling instant; Δ t is sampling interval duration; X is positive integer counter; The faulted phase current sampled value that i (t+x Δ t) is t+x Δ t sampling instant; for the faulted phase current sampled value of sampling instant; The faulted phase current sampled value that i (t+x Δ t-N Δ t) is t+x Δ t-N Δ t sampling instant; N is a cycle sampling number, ; T is the cycle time of fundametal compoment; I _efor transmission line rated current; K is tuning coefficient; α is tuning coefficient; β is tuning coefficient.

First the inventive method measures the faulted phase current instantaneous value of each sampling instant of transmission line current transformer installation place; choose two adjacent cycle faulted phase current sampled values and form Protection criteria; to faulted phase current waveform degree of asymmetry with whether there is discontiguous area and detect; if Protection criteria is set up; then judge transmission line generation single-phase high-impedance; send action trip signal, the circuit breaker at tripping transmission line two ends.The inventive method utilizes single end current to achieve the relaying protection of transmission line single-phase high-impedance, and performance is not subject to the impact of transition resistance and load current, can correct action message during transmission line single-phase high-impedance.The inventive method only need utilize single end current, and without the need to using voltage data, performance is not by the impact of Secondary Circuit of Potential Transformer broken string.

The foregoing is only preferred embodiment of the present invention; but protection scope of the present invention is not limited thereto; anyly be familiar with those skilled in the art in the technical scope that the present invention discloses, the change that can expect easily or replacement, all should be encompassed within protection scope of the present invention.

Claims (1)

1. utilize single end current to realize transmission line single-phase high-impedance relay protecting method, it is characterized in that, comprise following sequential steps:

The faulted phase current instantaneous value of each sampling instant of protector measuring transmission line current transformer installation place, the faulted phase current instantaneous value of each sampling instant utilizing it to measure calculates $\underset{x=0}{\overset{N-1}{\&Sigma;}}i(t+x\mathrm{\&Delta;}t)>k\underset{x=0}{\overset{N-1}{\mathrm{\&Sigma;}}}\&lsqb;i\left(t+x\mathrm{\&Delta;}t\right)+i\left(t+x\mathrm{\&Delta;}t-\frac{N}{2}\mathrm{\&Delta;}t\right)\&rsqb;$ With $\underset{x=0}{\overset{N-1}{\&Sigma;}}i(t+x\mathrm{\&Delta;}t)>{\mathrm{\&beta;I}}_e+$ $\mathrm{\&alpha;}\underset{x=0}{\overset{N-1}{\mathrm{\&Sigma;}}}\&lsqb;i\left(t+x\mathrm{\&Delta;}t\right)-i\left(t+x\mathrm{\&Delta;}t-N\mathrm{\&Delta;}t\right)\&rsqb;$ Whether set up, if set up simultaneously, then judge transmission line generation single-phase high-impedance, protective device sends action trip signal, the circuit breaker at tripping transmission line two ends simultaneously; Wherein, t is sampling instant; Δ t is sampling interval duration; X is positive integer variable; The faulted phase current sampled value that i (t+x Δ t) is t+x Δ t sampling instant; for the faulted phase current sampled value of sampling instant; The faulted phase current sampled value that i (t+x Δ t-N Δ t) is t+x Δ t-N Δ t sampling instant; N is a cycle sampling number, t is the cycle time of fundametal compoment; I _efor transmission line rated current; K is tuning coefficient; α is tuning coefficient; β is tuning coefficient.